ffmpeg | branch: master | Michael Niedermayer <mich...@niedermayer.cc> | Sat Jan 18 19:30:48 2025 +0100| [4a0c285dfef90face0961a56231031fde170f705] | committer: Michael Niedermayer
avcodec/ffv1: flip half of float16 and Compactify floats float16 (and more so float32) have many odd values half the values are negative, many are larger than "1.0" and many values are very close to 0. Storing the 16bits as is, looses compression because of the mixture of dense and sparse regions and also many completely unused ones. This simply remaps the 65536 values so no unused values remain This improves compression by about 1.5% for the ACES_OT_VWG_SampleFrames testset (this testset contains all kind of funny values including many images with negative rgb values) The space needed for the map is insignificant compared to the compression gained This patch also flips half the float range as it can be done using the same table. Sponsored-by: Sovereign Tech Fund Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4a0c285dfef90face0961a56231031fde170f705 --- libavcodec/ffv1.h | 1 + libavcodec/ffv1dec_template.c | 21 +++++++++++++++++++ libavcodec/ffv1enc_template.c | 49 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 71 insertions(+) diff --git a/libavcodec/ffv1.h b/libavcodec/ffv1.h index 87f0b2c02f..4ed06310f7 100644 --- a/libavcodec/ffv1.h +++ b/libavcodec/ffv1.h @@ -105,6 +105,7 @@ typedef struct FFV1SliceContext { uint64_t (*rc_stat2[MAX_QUANT_TABLES])[32][2]; }; }; + uint16_t fltmap[4][65536]; } FFV1SliceContext; typedef struct FFV1Context { diff --git a/libavcodec/ffv1dec_template.c b/libavcodec/ffv1dec_template.c index e983d1ba64..e11da1a66c 100644 --- a/libavcodec/ffv1dec_template.c +++ b/libavcodec/ffv1dec_template.c @@ -155,6 +155,20 @@ static int RENAME(decode_rgb_frame)(FFV1Context *f, FFV1SliceContext *sc, memset(RENAME(sc->sample_buffer), 0, 8 * (w + 6) * sizeof(*RENAME(sc->sample_buffer))); + if (f->flt) { + for (int p= 0; p<3 + transparency; p++) { + int j = 0; + int lu = 0; + uint8_t state[2] = {128, 128}; + for (int i= 0; i<65536; i++) { + int u = get_rac(&sc->c, state + lu); + sc->fltmap[p][j] = i ^ ((i&0x8000) ? 0 : 0x7FFF); + j+= u; + lu = u; + } + } + } + for (y = 0; y < h; y++) { for (p = 0; p < 3 + transparency; p++) { int ret; @@ -185,6 +199,13 @@ static int RENAME(decode_rgb_frame)(FFV1Context *f, FFV1SliceContext *sc, b += g; r += g; } + if (f->flt) { + r = sc->fltmap[0][r & 0xFFFF]; + g = sc->fltmap[1][g & 0xFFFF]; + b = sc->fltmap[2][b & 0xFFFF]; + if (transparency) + a = sc->fltmap[3][a & 0xFFFF]; + } if (lbd) *((uint32_t*)(src[0] + x*4 + stride[0]*y)) = b + ((unsigned)g<<8) + ((unsigned)r<<16) + ((unsigned)a<<24); diff --git a/libavcodec/ffv1enc_template.c b/libavcodec/ffv1enc_template.c index bc14926ab9..0d1b0a2843 100644 --- a/libavcodec/ffv1enc_template.c +++ b/libavcodec/ffv1enc_template.c @@ -148,6 +148,47 @@ static int RENAME(encode_rgb_frame)(FFV1Context *f, FFV1SliceContext *sc, memset(RENAME(sc->sample_buffer), 0, ring_size * MAX_PLANES * (w + 6) * sizeof(*RENAME(sc->sample_buffer))); + if (f->flt) { + memset(sc->fltmap, 0, sizeof(sc->fltmap)); + + for (y = 0; y < h; y++) { + for (x = 0; x < w; x++) { + int b, g, r, av_uninit(a); + + if (sizeof(TYPE) == 4 || transparency) { + g = *((const uint16_t *)(src[0] + x*2 + stride[0]*y)); + b = *((const uint16_t *)(src[1] + x*2 + stride[1]*y)); + r = *((const uint16_t *)(src[2] + x*2 + stride[2]*y)); + if (transparency) + a = *((const uint16_t *)(src[3] + x*2 + stride[3]*y)); + } else { + b = *((const uint16_t *)(src[0] + x*2 + stride[0]*y)); + g = *((const uint16_t *)(src[1] + x*2 + stride[1]*y)); + r = *((const uint16_t *)(src[2] + x*2 + stride[2]*y)); + } + + sc->fltmap[0][r] = 1; + sc->fltmap[1][g] = 1; + sc->fltmap[2][b] = 1; + if (transparency) + sc->fltmap[3][a] = 1; + } + } + for (int p= 0; p<3 + transparency; p++) { + int j = 0; + int lu = 0; + uint8_t state[2] = {128, 128}; + for (int i= 0; i<65536; i++) { + int ri = i ^ ((i&0x8000) ? 0 : 0x7FFF); + int u = sc->fltmap[p][ri]; + sc->fltmap[p][ri] = j; + j+= u; + put_rac(&sc->c, state + lu, u); + lu = u; + } + } + } + for (y = 0; y < h; y++) { for (i = 0; i < ring_size; i++) for (p = 0; p < MAX_PLANES; p++) @@ -180,6 +221,14 @@ static int RENAME(encode_rgb_frame)(FFV1Context *f, FFV1SliceContext *sc, r = *((const uint16_t *)(src[2] + x*2 + stride[2]*y)); } + if (f->flt) { + r = sc->fltmap[0][r]; + g = sc->fltmap[1][g]; + b = sc->fltmap[2][b]; + if (transparency) + a = sc->fltmap[3][a]; + } + if (sc->slice_coding_mode != 1) { b -= g; r -= g; _______________________________________________ ffmpeg-cvslog mailing list ffmpeg-cvslog@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-cvslog To unsubscribe, visit link above, or email ffmpeg-cvslog-requ...@ffmpeg.org with subject "unsubscribe".
